Functionalized metal complexes

ABSTRACT

Described herein are metal complexes having the formula  
                 
 
     wherein M is nickel, palladium, or platinum; Q 1 -Q 4  are each independently sulfur, selenium, or tellurium; X 1 -X 4  are each independently a divalent linking group having 1 to about 125 carbons; m1 to m4 are each independently 0 or 1; and W 1 -W 4  are each independently hydrogen, carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonyl chloride, with the proviso that W 1 -W 4  are not all hydrogen. The complexes have strong absorptions in the near infrared.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Provisional Application SerNo. 60/378,179, filed May 2, 2002, which is incorporated herein byreference in its entirety.

BACKGROUND

[0002] Transition metal dithiolene complexes and their selenium andtellurium analogs have been extensively studied. Reviews of work in thisarea include, for example, U. T. Mueller-Westerhoff and B. Vance,“Dithiolenes and Related Species”, Chapter 16.5 in G. Wilkinson, Ed.“Comprehensive Coordination Chemistry”, Pergamon Press, 1987. Some ofthese complexes are of interest for their oxidation-reductionproperties, as well as their ability to efficiently absorb near infraredradiation and thermally dissipate the absorbed energy.

[0003] In order to covalently bind a metal dithiolene complex to anothermolecule, it would be desirable to begin with a metal dithiolenecomplexes having a reactive functional group. In practice, however, ithas been difficult to prepare such complexes because the formationand/or presence of the functional groups has interfered with metalcomplexation by the dithiolene ligand. There therefore remains a needfor functionalized metal dithiolene complexes.

BRIEF SUMMARY

[0004] Described herein is a composition comprising a metal complexhaving the formula (I)

[0005] wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are eachindependently sulfur, selenium, or tellurium; X¹-X⁴ are eachindependently a divalent linking group having 1 to about 125 carbons; m1to m4 are each independently 0 or 1; and W¹ -W⁴ are each independentlyhydrogen, carboxylic acid, carboxylic acid anhydride, carboxylic acidchloride, sulfonic acid, or sulfonyl chloride, with the proviso thatW¹-W⁴ are not all hydrogen.

[0006] Other embodiments, including functionalizedferrocenyl-substituted metal complexes and functionalized bis-metalcomplexes, are described below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] One embodiment is a composition comprising a functionalized metalcomplex having formula (I)

[0008] wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are eachindependently sulfur, selenium, or tellurium; X¹-x⁴ are eachindependently a divalent linking group having 1 to about 125 carbons; mlto m4 are each independently 0 or 1; and W¹-W⁴ are each independentlyhydrogen, carboxylic acid, carboxylic acid anhydride, carboxylic acidchloride, sulfonic acid, or sulfonyl chloride, with the proviso thatW¹-W⁴ are not all hydrogen.

[0009] In a preferred embodiment, M is nickel. In another preferredembodiment, Q¹-Q⁴ are sulfur.

[0010] Although the metal complexes are herein represented for brevityas having the dithiolene structural unit as follows:

[0011] it will be understood that various oxidation states are availableto the metal such that the complex can be represented as any one or moreof the redox-related complexes as shown below

[0012] and corresponding to metal oxidation states of 0 to +4. Suchstructures, and any others that may be present, are within the scope ofthe dithiolene structure.

[0013] In one embodiment, each occurrence of X¹-X⁴ is independently—(CH₂)_(n1)— wherein n1 is 1 to 24, —(V(CH₂)_(p))_(n2)— where V isoxygen or sulfur and p is 2 or 3 and n2 is 1 to 12, —N(R²)—(CH₂)_(n3)—where n3 is 1 to 24 and R² is C₁-C₁₂ alkyl, —C(O)(CH₂)_(n4)— where n4 is1 to 23, —C(O)N(R³)(CH₂)_(n5)— where n5 is 1 to 23 and R³ is hydrogen orC₁-C₁₂ alkyl, —N(R⁴)—S(O)₂(CH₂)_(n6)— where n6 is 1 to 24 and R⁴ ishydrogen or C₁-C₁₂ alkyl, —S(CH₂)_(n7)— where n7 is 1 to 24,—S(O)(CH₂)_(n8)— where n8 is 1 to 24, —S(O)₂—(CH₂)_(n9)— where n9 is 1to 24, or —S(O)₂—N(R⁵)—(CH₂)_(n10)— wherein n10 is 1 to 24 and R⁵ ishydrogen or C₁-C₁₂ alkyl. It will be understood that either terminus ofa given X¹-X⁴ group above may be attached to the corresponding W¹-W⁴group, with the other terminus attached to the corresponding dithiolenecarbon. For example, when X¹ is —N(R²)(CH₂)_(n3)—, it may be attached inthe configuration W¹—N(R²)(CH₂)_(n3)-(dithiolene)—or in theconfiguration W¹—(CH₂)_(n3)N(R²)-(dithiolene)-.

[0014] In a preferred embodiment each occurrence of W¹-W⁴ isindependently carboxylic acid (—C(O)OH); carboxylic acid anhydride(—C(O)OC(O)R) wherein R is C₁-C₁₂ alkyl or C₆-C₁₂ aryl; or carboxylicacid chloride (—C(O)Cl). In a highly preferred embodiment, eachoccurrence of W¹-W⁴ is independently carboxylic acid.

[0015] In another embodiment, at least one of X¹-X⁴ comprises aferrocenyl complex. For example, at least one of X¹-X⁴ may have thestructure of formula (II)

[0016] wherein n13 is 1 to about 12, and the value of the correspondingm1-m4 is one. In other words, X¹ has the divalent ferrocenyl structureshown above and ml is one, and/or X² has the divalent ferrocenylstructure shown above and m2 is one, and/or X³ has the divalentferrocenyl structure shown above and m3 is one, and/or X⁴ has thedivalent ferrocenyl structure shown above and m4 is one. In a preferredembodiment, at least two of X¹-X⁴ have the divalent ferrocenyl structureshown above and the values of the corresponding at least two of m1-m4are one. It will be understood that as used herein, the cyclopentadienylrings of all ferrocenyl moieties shown and described in this applicationmay include alkyl-substituted analogs, preferably branched or unbranchedC₁-C₈ alkyl-sustituted analogs, including, for example,methycyclopentadienyl, dimethylcyclopentadienyl,trimethylcyclopentadieny, tetramethylcyclopentadienyl, andpentamethylcyclopentadienyl. Varying the degree of alkylation ofcyclopentadienyl rings may be used to control the maximum absorptionwavelength of the complex.

[0017] In another embodiment, the metal complex has one of thestructures of Formula (IIIa)-(IIIc):

[0018] wherein M, Q¹-Q⁴, W² and W³ are as defined above for formula (I),and n13 is as defined above for Formula (II). Compounds of Formula (III)have the advantage of absorbing strongly in the region of about 1600 toabout 1900 nanometers.

[0019] Preferably, each occurrence of W¹-W⁴ is independently carboxylicacid (—C(O)OH); carboxylic acid anhydride (—C(O)OC(O)R) wherein R isC₁-C₁₂ alkyl or C₆-C₁₂ aryl; or carboxylic acid chloride (—C(O)Cl). In ahighly preferred embodiment, each occurrence of W¹-W⁴ is independentlycarboxylic acid. According, in a preferred embodiment, thefunctionalized metal complex has formula (IV)

[0020] Another embodiment is a composition comprising a functionalizedmetal complex having formula (V)

[0021] wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are eachindependently sulfur, selenium, or tellurium; Ar¹-Ar⁴ are eachindependently C₆-C₁₂ arylene, wherein Ar and Ar² may collectively form aC₂-C₂₄ arylene, and Ar³ and Ar⁴ may collectively form a C₁₂-C₂₄ arylene;each occurrence of R¹-R⁴ is independently C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy,C₁-C₁₂ alkylthio, halogen, hydroxy, nitro, cyano, di(C₁-C₁₂)alkylamino,or sulfonamide; each occurrence of p1-p4 is independently 0, 1, 2, 3, 4,or 5; each occurrence of Y¹-Y⁴ is independently a divalent linking grouphaving 1 to about 125 carbons; each occurrence of q1-q4 is independently0 or 1; each occurrence of Z¹-Z⁴ is independently carboxylic acid,carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, orsulfonyl chloride; and each occurrence of r1-r4 is independently 0, 1,2, or 3, with the proviso that at least one of r1-r4 is at least 1.

[0022] Referring to formula (V), in a preferred embodiment, M is nickel.In another preferred embodiment, Q¹-Q⁴ are sulfur. In addtion, Ar¹-Ar⁴are each independently phenylene, diphenylene, naphthylene, orjulolidinylene; or Ar¹ and Ar² collectively form a 2,2′-diphenylene andAr³ and Ar⁴ collectively form a 2,2′-diphenylene, wherein2,2′-diphenylene is understood to have the structure

[0023] In a preferred embodiment, Ar¹-Ar⁴ are each phenylene.

[0024] Referring still to formula (V), in one embodiment at least one ofR¹-R⁴ is an electron donating substituent such as di(C₁-C₁₂)alkylamino,and the value of the corresponding at least one p1-p4 is at least 1. Itmay be preferred that at least two of R¹-R⁴ are electron donatingsubstituents such as di(C₁-C₁₂)alkylamino, and the values of thecorresponding at least two of p1 -p4 are at least 1.

[0025] In one embodiment, each occurrence of Y¹-Y⁴ is independently—(CH₂)_(n1)— wherein n1 is 1 to 24, —(OCH₂CH₂)_(n2)— where n2 is 1 to12, —N(R²)(CH₂)_(n3)— where n3 is 1 to 24 and R² is C₁-C₁₂ alkyl,C(O)(CH₂)_(n4)— where n4 is 1 to 23, —C(O)—N(R³)—(CH₂)_(n5)— where n5 is1 to 23 and R³ is hydrogen or C₁-C₁₂ alkyl, —N(R⁴)S(O)₂(CH₂)_(n6)— wheren6 is 1 to 24 and R⁴ is hydrogen or C₁-C₁₂ alkyl, —S(CH₂)_(n7)— where n7is 1 to 24, —S(O)(CH₂)_(n8)— where n8 is 1 to 24, —S(O)₂(CH₂)_(n9)—where n9 is 1 to 24, or —S(O)₂—N(R⁵)(CH₂)_(n10)— where n10 is 1 to 24and R⁵ is hydrogen or C₁-C₁₂ alkyl. It will be understood that eitherterminus of a given Y¹-Y⁴ group above may be attached to thecorresponding Z¹-Z⁴ group, with the other terminus attached to thecorresponding Ar¹-Ar⁴. For example, when Y¹ is —N(R²)(CH₂)_(n3)—, it maybe attached in the configuration Z¹—N(R²)(CH₂)_(n3)—Ar¹— or in theconfiguration Z¹—(CH₂)_(n3)N(R²)—Ar¹—.

[0026] In a preferred embodiment, each occurrence of Y¹-Y⁴ isindependently —(CH₂)_(n1)— wherein n1 is 1 to 24, or —N(R²)(CH₂)_(n3)—where n3 is 1 to 24 and R² is hydrogen or C₁-C₁₂ alkyl.

[0027] In another embodiment, at least one of Y¹-Y⁴ comprises a divalentpolypeptide, a divalent polysaccharide, or a divalent polynucleotide.

[0028] Still referring to formula (V), in a preferred embodiment eachoccurrence of Z¹-Z⁴ is independently carboxylic acid (—C(O)OH);carboxylic acid anhydride (—C(O)OC(O)R) wherein R is C₁-C₁₂ alkyl orC₆-C₁₂ aryl; or carboxylic acid chloride (—C(O)Cl). In a highlypreferred embodiment, each occurrence of W¹-W⁴ is independentlycarboxylic acid.

[0029] In another preferred embodiment, at least two of r1-r4 are atleast 1.

[0030] Another embodiment is a composition comprising a functionalizedmetal dithiolene complex having formula (VI)

[0031] wherein M is nickel, palladium, or platinum; each occurrence ofR¹-R⁴ is independently C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₁-C₁₂ alkylthio,halogen, hydroxy, nitro, cyano, di(C₁-C₁₂)alkylamino, or sulfonamide;each occurrence of p1-p4 is independently 0, 1, 2, 3, 4, or 5; eachoccurrence of Y¹-Y⁴ is independently a divalent linking group having 1to about 125 carbons; each occurrence of q1-q4 is independently 0 or 1;each occurrence of Z¹-Z⁴ is independently carboxylic acid, carboxylicacid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonylchloride; and each occurrence of r1-r4 is independently 0, 1, 2, or 3,with the proviso that at least one of r1-r4 is at least 1.

[0032] In a preferred embodiment, M is nickel.

[0033] Another embodiment is a composition comprising a functionalizedmetal dithiolene complex having formula (VII)

[0034] wherein M is nickel, palladium, or platinum; each occurrence ofR⁶ is independently C₁-C₁₂ alkyl; each occurrence of X is independently—CH₂— or —C(O); and each occurrence of n11 is independently 1 to 24.

[0035] Another embodiment is a composition comprising a functionalizedbis-metal dithiolene complex having formula (VIII)

[0036] wherein n12 is 0 to about 8, preferably 1 to about 6; and M, R⁶,X, and n11 are as defined above for formula (VI).

[0037] Another embodiment is a composition comprising a functionalizednickel dithiolene complex having formula (IX)

[0038] Compounds of the generalized formula (VII) can be obtained byfirst synthesizing the two halves of each ligand, or protectedderivatives thereof, in the form of their aldehydes (A) (e.g., A1 andA2, below); then condensing the two halves by one of several methods,such as benzoin condensation or Corey-Seeback umpolung reaction or thelike to form B (e.g., B1, below) or one of its derivatives; thenconverting B to the dithiolene complex VI as described in theliterature.

[0039] Compounds of the generalized formula (VIII), in which theextinction coefficients are multiplied by attaching several dithiolenesto the same backbone, can be prepared using the syntheses shown below inwhich (VII) is an intermediate. By reaction with SOCl₂ or (COCl)₂, (VII)is converted to the acid chloride, which then is added to the polyamineC dissolved in ether or dichloromethane. After addition of an aqueoussodium acetate solution to hydrolyze the unreacted acid chloridefunctions and acidification to pH 5, the bound dithiolene is isolatedand purified.

[0040] Compounds of structure (IX) may be synthesized by the route shownbelow. Starting from the commercially available cyano-aldehyde D(Aldrich), a benzoin condensation with benzaldehyde produces the benzoinintermediate E. Refluxing E with phosphorus pentasulfide in dioxane,followed by addition of metal chloride (NiCl₂ in the case of (IX), M=Ni)in water and another period of reflux produces the dithiolene F andseveral byproducts. Separation of F by column chromatography is followedby hydrolysis of the cyano groups through stirring F at room temperaturefor 24 h in a solution of concentrated HCl in glacial acetic acid toproduce (IX).

[0041] The functionalized metal complex preferably has an extinctioncoefficient of at least about 10,000 M⁻¹cm⁻¹ at a wavelength of about800 to about 2000 nanometers. The extinction coefficient may preferablybe at least about 20,000 M⁻¹cm⁻¹, more preferably at least about 30,000M⁻¹cm⁻¹, still more preferably at least about 40,000 M⁻¹cm⁻¹, yet morepreferably at least about 60,000 M⁻¹cm⁻¹, even more preferably at leastabout 80,000 M⁻¹cm⁻¹. In one embodiment, the wavelength may preferablybe at least about 900 nm and up to about 1350 nm. In another embodiment,the wavelength may preferably be at least about 1650 nm and up to about1900 nm.

[0042] The functionalized metal complex preferably does notsignificantly fluoresce or phosphoresce. For example, the functionalizedmetal complex may have a fluorescence and/or phosphorescence quantumyield of less than or equal to 0.05 for an excitation wavelength ofabout 800 to about 2000 nanometers. When the metal complex has such lowquantum yield for fluorescence and phosphorescence, essentially allabsorbed near infrared (NIR) light energy is converted to thermal energythat can be used to heat up the immediate environment of the complex.

[0043] The functionalized metal complexes described herein are useful asredox catalysts, as efficient converters of near-infrared radiation tothermal energy, and as conductors of electric current. They may alsoexhibit unusual magnetic properties. They are also useful as substratesin passive Q-switch and mode-locking applications for different IRlasers (see, for example, U.S. Pat. No. 3,743,964 to Drexhage et al.).They are further useful as redox potential driven electron carriers andcation carriers through artificial membranes (see, for example, J. J.Grimaldi and J. M. Lehn, J. Am. Chem. Soc., 1979, volume 101, pages 1333ff.; and A. Ohki, M. Takagi, and K. Ueno, Chem. Lett., 1980, pages 1591ff.).

[0044] The invention is further illustrated by the followingnon-limiting examples.

EXAMPLE 1

[0045] This example describes preparation of a functionalized,bis(ferrocenyl)-substituted nickel dithiolene complex. The procedure ofWilkes et al. was used to react α-chloroacetylferrocene (obtained fromAldrich) with ferrocene and aluminum chloride in dichloromethane toproduce chloroacetylferrocene. This was reacted with potassiumethylxanthate in ethanol; the product of this reaction was cyclized toform a ferrocenyl dithiocarbonate (4-ferrocenyl-1,3-dithiole-2-one).(See A. E. Underhill, A. Charlton, S. B. Wilkes, I. R. Butler, A.Kobayashi, and H. Kobayashi, Synth. Met., 1995, volume 70, pages 1101ff.)

[0046] The ferrocenyl dithiocarbonate was reacted with one equivalent ofsuccinic anhydride and three equivalents of aluminum chloride. An 82.7%yield of 4-(1′-succinylferrocenyl)-1,3-dithiole-2-one was obtainedfollowing purification by column chromatography.

[0047] The 6,7-(1′-succinyl)ferrocenyl-3,4-dithiole-2-one was reactedwith potassium hydroxide in methanol to form the dithiolate dianion;addition of nickel chloride hexahydrate in methanol/HCl yielded thesuccinyl-substituted diferrocenyl nickel complex, bis([1′-succinylferrocenyl]ethylene-1,2-dithiolato) nickel (II). The product wasconverted to the neutral nickel (IV) complex by oxidizing with air.

[0048] Following oxidation, workup, and isolation of the productmixture, the complex was dissolved in an aqueous 10% KOH solution andfiltered. Product was precipitated by acidifying the solution to pH 3,filtered, and washed with water and then hexane to afford the purifiedcomplex in 48% yield based on the dithiolene ligand. mp >260° C.; APcI⁻MS m/e 805.7 (M⁻, calc. 805.88); Near IR λ_(1max)/λ_(2max) (CH₂Cl₂) 1106nm (broad, strong)/735 nm, (DMF) 1140 nm (broad, strong)/752 nm, (DMF)1007 nm (monoanionic species, (H₂O, pH 3) 1180 nm (broad, strong)/748nm, (H₂O, pH 7.5) 1068 nm, (H₂O, pH 9) 163 nm.

EXAMPLE 2

[0049] This example summarized procedures used in multiple preparationsof a functionalized bis(dialkylamino)-substituted nickel dithiolenecomplex. The commercially available (Aldrich) material4-(2-cyanoethyl-methylamino)benzaldehyde was subjected to a benzoincondensation with benzaldehyde (NaCN catalyst in either ethanol/water orN,N-dimethylformamide/water at temperatures varying between 20° C. andthe boiling point of the reaction mixture) to produce a mixture ofproducts, of which the desired benzoin was a more or less abundant part.Optimization of the reaction conditions allowed the synthesis of thebenzoin as the major product. The purification involved repeated columnchromatography and recrystallizations for an overall yield of purebenzoin varying between 25 and 60%. In this manner, sufficientquantities of the benzoin were obtained to proceed to the next step.

[0050] The benzoin was treated with P₄S₁₀ in dioxane (reflux, 2 h) andthe mixture was reacted at reflux with NiCl₂-6H₂O in water containingHCl to produce the dithiolene complex carrying two cyanofunctionalities. This complex was purified by column chromatography.

[0051] In the final step, the dicyano derivative was hydrolyzed(anyhydrous HCl/acetic acid, room temperature, 2 days) to produce thedesired diacid.

[0052] The product was recrystallized from ethyl acetate andcharacterized by Vis-NIR spectroscopy (λ_(max)=1058 nm) and APcI massspectrometry. The success of this synthetic approach was not necessarilyexpected because the cyano group could have interfered in thesulfurization reaction, and the final hydrolysis could have destroyedthe dithiolene complex.

[0053] While the invention has been described with reference to apreferred embodiment, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof Therefore, it is intended that the invention notbe limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

[0054] All cited patents, patent applications, and other references areincorporated herein by reference in their entirety.

What is claimed is:
 1. A composition comprising a metal complex having the formula

wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are each independently sulfur, selenium, or tellurium; X¹-X⁴ are each independently a divalent linking group having 1 to about 125 carbons; m1 to m4 are each independently 0 or 1; and W¹-W⁴ are each independently hydrogen, carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonyl chloride, with the proviso that W¹-W⁴ are not all hydrogen.
 2. The composition of claim 1, wherein M is nickel.
 3. The composition of claim 1, wherein Q¹-Q⁴ are sulfur.
 4. The composition of claim 1, wherein each X¹-X⁴ is independently —(CH₂)_(n1)— wherein n1 is 1 to 24, —(V(CH₂)_(p))_(n2)— where V is oxygen or sulfur and p is 2 or 3 and n2 is 1 to 12, —N(R²)(CH₂)_(n3)— where n3 is 1 to 24 and R² is C₁-C₁₂ alkyl, —C(O)(CH₂)_(n4)— where n4 is 1 to 23, —C(O)N(R³)(CH₂)_(n5)— where n5 is 1 to 23 and R³ is hydrogen or C₁-C₁₂ alkyl, —N(R⁴)S(O)₂(CH₂)_(n6)— where n6 is 1 to 24 and R⁴ is hydrogen or C₁-C₁₂ alkyl, —S(CH₂)_(n7)— where n7 is 1 to 24, —S(O)(CH₂)_(n8)— where n8 is 1 to 24, —S(O)₂(CH₂)_(n9)— where n9 is 1 to 24, or —S(O)₂N(R⁵)(CH₂)_(n10)— where n10 is 1 to 24 and R⁵ is hydrogen or C₁-C₁₂ alkyl.
 5. The composition of claim 1, wherein at least one of X¹-X⁴ is

wherein n13 is 1 to about 12, and the value of the corresponding m1-m4 is one.
 6. The composition of claim 1, wherein each occurrence of W¹-W⁴ is independently a carboxylic acid, a carboxylic acid anhydride of the formula —C(O)OC(O)R wherein R is C₁-C₁₂ alkyl or C₆-C₁₂ aryl, or a carboxylic acid chloride.
 7. The composition of claim 1, wherein each occurrence of W¹-W⁴ is carboxylic acid.
 8. The composition of claim 1, wherein the metal complex has an extinction coefficient of at least about 10,000 M⁻¹cm⁻¹ at a wavelength of about 800 to about 2000 nanometers.
 9. The composition of claim 1, wherein the metal complex has an extinction coefficient of at least about 20,000 M⁻¹cm⁻¹ at a wavelength of about 900 to about 1350 nanometers.
 10. The composition of claim 1, wherein the metal complex has an extinction coefficient of at least about 20,000 M⁻¹cm⁻¹ at a wavelength of about 1650 to about 1900 nanometers.
 11. The composition of claim 1, wherein the metal complex has a fluorescence and/or phosphorescence quantum yield of less than or equal to 0.05 for an excitation wavelength of about 800 to about 2000 nanometers.
 12. A composition comprising a metal complex having the formula

wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are each independently sulfur, selenium, or tellurium; Ar¹-Ar⁴ are each independently C₆-C₁₂ arylene, wherein Ar¹ and Ar² may collectively form a C₁₂-C₂₄ arylene, and Ar³ and Ar⁴ may collectively form a C₁₂-C₂₄ arylene; each occurrence of R¹-R⁴ is independently C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₁-C₁₂ alkylthio, halogen, hydroxy, nitro, cyano, di(C₁-C₁₂)alkylamino, or sulfonamide; each occurrence of p1-p4 is independently 0, 1, 2, 3, 4, or 5; each occurrence of Y¹-Y⁴ is independently a divalent linking group having 1 to about 125 carbons; each occurrence of q1-q4 is independently 0 or 1; each occurrence of Z¹-Z⁴ is independently carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonyl chloride; and each occurrence of r1-r4 is independently 0, 1, 2, or 3, with the proviso that at least one of r1-r4 is at least
 1. 13. The composition of claim 12, wherein M is nickel.
 14. The composition of claim 12, wherein Q¹-Q⁴ are sulfur.
 15. The composition of claim 12, wherein Ar¹-Ar⁴ are each independently phenylene, diphenylene, naphthylene, or julolidinylene; or Ar¹ and Ar² collectively form a 2,2′-diphenylene and Ar³ and Ar⁴ collectively form a 2,2′-diphenylene.
 16. The composition of claim 12, wherein Ar¹-Ar⁴ are each phenylene.
 17. The composition of claim 12, wherein at least one of R¹-R⁴ is di(C₁-C₁₂)alkylamino and the value of the corresponding p1-p4 is at least
 1. 18. The composition of claim 12, wherein each occurrence of Y¹-Y⁴ is independently —(CH₂)_(n1)— wherein n1 is 1 to 24, —(OCH₂CH₂)_(n2)— where n2 is 1 to 12, —N(R²)(CH₂)_(n3)— where n3 is 1 to 24 and R² is C₁-C₁₂ alkyl, —C(O)(CH₂)_(n4)— where n4 is 1 to 23, —C(O)N(R³)(CH₂)_(n5)— where n5 is 1 to 23 and R³ is hydrogen or C₁-C₁₂ alkyl, —N(R⁴)S(O)₂(CH₂)_(n6)— where n6 is 1 to 24 and R⁴ is hydrogen or C₁-C₁₂ alkyl, —S(CH₂)_(n7)— where n7 is 1 to 24, —S(O)(CH₂)_(n8)— where n8 is 1 to 24, —S(O)₂(CH₂)_(n9)— where n9 is 1 to 24, or —S(O)₂N(R⁵)(CH₂)_(n10)— where n10 is 1 to 24 and R⁵ is hydrogen or C₁-C₁₂ alkyl.
 19. The composition of claim 12, wherein each occurrence of Y¹-Y⁴ is independently —(CH₂)_(n1)— wherein n1 is 1 to 24, or —N(R²)(CH₂)_(n3)— where n3 is 1 to 24 and R² is hydrogen or C₁-C₁₂ alkyl.
 20. The composition of claim 12, wherein one to three of Y¹-Y⁴ comprises a divalent polypeptide, a divalent polysaccharide, or a divalent polynucleotide.
 21. The composition of claim 12, wherein each occurrence of Z¹-Z⁴ is independently a carboxylic acid, a carboxylic acid anhydride of the formula —C(O)OC(O)R wherein R is C₁-C₁₂ alkyl or C₆-C₁₂ aryl, or a carboxylic acid chloride.
 22. The composition of claim 11, wherein each occurrence of Z¹-Z⁴ is carboxylic acid.
 23. The composition of claim 11, wherein at least two of r1-r4 are at least
 1. 24. A composition comprising a metal complex having the formula

wherein M is nickel, palladium, or platinum; each occurrence of R¹-R⁴ is independently C₁-C₁₂ alkyl, C₁-C₁₂ alkoxy, C₁-C₁₂ alkylthio, halogen, hydroxy, nitro, cyano, di(C₁-C₁₂)alkylamino, or sulfonamide; each occurrence of p1-p4 is independently 0, 1, 2, 3, 4, or 5; each occurrence of Y¹-Y⁴ is independently a divalent linking group having 1 to about 125 carbons; each occurrence of q1-q4 is independently 0 or 1; each occurrence of Z¹-Z⁴ is independently carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonyl chloride; and each occurrence of r1-r4 is independently 0, 1, 2, or 3, with the proviso that at least one of r1-r4 is at least
 1. 25. The composition of claim 24, wherein M is nickel.
 26. The composition of claim 24, having the formula

wherein M is nickel, palladium, or platinum; each occurrence of R⁶ is independently C₁-C₁₂ alkyl; each occurrence of X is independently —CH₂— or —C(O)—; and each occurrence of n11 is independently 1 to
 24. 27. The composition of claim 26, comprising a nickel dithiolene complex having the formula


28. A composition comprising a metal dithiolene complex having the formula

wherein M is nickel, palladium, or platinum; each occurrence of R⁶ is independently C₁-C₁₂ alkyl; each occurrence of X is independently —CH₂— or —C(O)—; each occurrence of n11 is independently 1 to 24; and n12 is 0 to
 8. 29. The composition of claim 1 comprising a nickel dithiolene complex having the formula

wherein M is nickel, palladium, or platinum; Q¹-Q⁴ are each independently sulfur, selenium, or tellurium; W² and W³ are each independently hydrogen, carboxylic acid, carboxylic acid anhydride, carboxylic acid chloride, sulfonic acid, or sulfonyl chloride; and each n13 is independently 1 to
 12. or a combination thereof. 